Lipid metabolism in Mucor genevensis and related species
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Date
1999-11
Authors
Pohl, Carolina Henritta
Journal Title
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Publisher
University of the Free State
Abstract
English: In this study the lipid metabolism of Mucor genevensis and related mucoralean fungi
have been explored. Consequently, endogenous lipid turnover during growth and
development of the different asexual and sexual reproductive stages, was studied in
Mucor genevensis MUFS 038. Lipid analyses were periodically performed on
cultures growing on solid synthetic media. It was found that during all developmental
stages, the lipid composition remained similar to that of a typical mucoralean fungus.
However, zygospores were found to have fewer membranes (i.e. less phospholipids)
with a lower degree of fluidity (i.e. less polyunsaturated fatty acids - PUFAs) than
sporangiospores and mycelium. Decreases in neutral, glyco- and phospholipids were
observed during sporogenesis. The aim of the next chapter was to investigate the
uptake and incorporation of arachidonic acid [20:4((,)6)] into the various lipid fractions
of Mucor genevensis MUFS 038 and Rhizopus oryzae PPRI 5172. The exogenous
20:4((ยท)6) was rapidly taken up by the fungi. The overall concentration of 20:4((,)6) in
both fungi decreased due to catabolism of 20:4((1)6). The PUFA was incorporated
into the neutral, glyco- and phospholipids of both fungi. 1t was found that Rhizopus
oryzae has a greater ability to reduce the amount of cellular free 20:4((!)6) than M.
genevensis. During incubation with 20:4((!)6), different changes in the concentrations
of 16 and 18 carbon fatty acids were observed for the two fungi, indicating differences
in lipid metabolism of these two fungi. In the next chapter, mucoralean fungi werescreened for oxidation products of exogenous PUFAs. Lipid extracts from biomass
and aqueous phases of cultures of the following strains were analysed using gas
chromatography-mass spectrometry: Mucor circinelloides f. circinelloides CBS
107.16, Mucor flavus CBS 234.35, Mucor genevensis MUFS 038, Mucor mucedo
CBS 109.16, Mucor plumbeus CBS 111.07, Rhizopus oryzae PPRI 5172 and
Thamnostylum piriforme MUFS 025. The following PUFAs were fed to the fungal
cultures: linoleic acid, y-linolenic acid, dihomo-y-linolenic acid [20:3((,)6)], 20:4((1)6) and
eicosapentaenoic acid. It was demonstrated that M. genevensis and M. circinelloides are able to produce 3-hydroxy-5,8-tetradecadienoic acid (3-HTDE) from 20:4(0)6) and
20'3((,)6), respectively No other 3-hydr0X~1 fatty acids (3-0H-FAs) were detected in
any other strains. It was suggested that the 3-0H-FAs were produced at such low
concentrations that detection was impossible in most of the strains. Another reason .'
for the apparent absence of 3-0H-FAs may be that these compounds are rapidly
utilised or further metabolised by the strains. Detection of 3-HTDE in the aqueous
phase only, suggested that it was not a structural component of membranes, or that
3-HTDE was formed at a pnvsiotoqica: stage which did not contribute to the final
biomass. Subsequently, immunofluorescence microscopy was used in the
localisation of endogenous 3-0H-FAs in M. genevensis MUFS 038. It was found that
3-0H-FAs are associated with spore bearing structures. It was speculated that some
of the lipids, which diminish during sporogenesis of M. genevensis, were transformed
to hydroxylated fatty acids during sporogenesis.
Afrikaans:In hierdie studie is die lipiedmetabolisme van Mucor genevensis en verwante spesies ondersoek. Gevolglik is die endogene lipiedomset gedurende groei en ontwikkeling van die verskillende ongeslagtelike en geslagtelike voortplantingsfases van Mucor genevensis MUFS 038 bestudeer. Lipiedanalises is met tussenpose op kulture wat op soliede sintetiese media gekweek is, uitgevoer. Dit is gevind dat, gedurende al die ontwikkelingsfases, die lipiedsamestelling vergelykbaar was met die van 'n tipiese mucoraliese fungus. Zigospore het egter minder membrane (d.i. minder fosfolipiede) met 'n laer graad van vloeibaarheid (d.i. minder poli-onversadigde vetsure - POVs) gehad as sporangiospore en miselium. Afnames in neutrale, gliko- en fosfolipiede is waargeneem tydens sporogenese. Die doel van die volgende hoofstuk was om die opname en inkorporasie van araqidonsuur [20:4((06)] in die verskillende lipiedfraksies van Mucor genevensis MUFS 038 en Rhizopus oryzae PPRI 5172, te bestudeer. Die eksogene 20:4((,)6) is vinnig deur die fungi opgeneem. Die algehele konsentrasie 20:4((1)6) in beide fungi het afgeneem a.g.v. die katabolisme van 20:4((1)6). Die POV is geรฏnkorporeer in die neutrale, gliko- en fosfolipiede van beide fungi. Dit is gevind dat Rhizopus oryzae 'n groter vermoรซ as M. genevensis het om die hoeveelheid vrye 20:4((1)6) in die selle te verminder. Tydens inkubasie met 20:4((1)6), is verskillende veranderinge in die konsentrasies van 16- en 18-koolstof vetsure vir die twee fungi waargeneem. Dit dui op verskille tussen die lipiedmetabolismes van die twee fungi. In die volgende hoofstuk is mucoraliese fungi ondersoek vir die vorming van oksidasieprodukte vanaf eksogene POVs. Lipiedekstrakte van biomassa en vloeistoffases van kulture van die volgende stamme is geanaliseer d.m.V. gaschromatografie-massa spektrometrie: Mucor circinelloides f. circinelloides CBS 107.16, Mucor flavus CBS 234.35, Mucor genevensis MUFS 038, Mucor mucedo CBS 109.16, Mucor plumbeus CBS 111.07, Rhizopus oryzae PPRI 5172 en Thamnostylum piriforme MUFS 025. Die volgende POVs is vir die fungikulture gevoer: linoleiensuur, y-linoleensuur, dihomo-y-linoleensuur [20:3((1)6)], 20:4(0)6) en eikosapentanoรซsuur. Dit is gedemonstreer dat M. genevensis en M. circinelloides 3- hidroksie-5,8-tetradekadienoรซsuur (3-HTDE) vanaf 20:4((06) en 20:3((06) onderskeidelik, kan produseer. Geen ander 3-hidroksievetsure (3-0H-VSs) is in die ander stamme waargeneem nie. Dit word voorgestel dat die 3-0H-VSs in die meeste stamme teen te lae konsentrasies geproduseer is en dus nie waargeneem kon word nie. 'n Ander rede vir die skynbare afwesigheid van 3-0H-VSs kan wees dat hierdie verbindings vinnig deur hierdie stamme verbruik of verder gemetaboliseer word. Deteksie van 3-0H-VSs slegs in die vloeistoffase, het daarop gedui dat dit nie strukturele komponente van membrane was nie, of dat 3-HTDE gevorm is tydens 'n fisiologiese fase wat nie tot die finale biomassa bygedra het nie. Hierna is immunofluoressensiemikroskopie gebruik om die ligging van endogene 3-0H-VSs in M. genevensis MUFS 038 te bepaal. Dit is gevind dat 3-0H-VSs geassosieer word met spoordraende strukture. Dit is gespekuleer dat sommige lipiede, wat verminder tydens sporogenese van M. genevensis, getransformeer is na gehidroksileerde vetsure tydens sporogenese.
Afrikaans:In hierdie studie is die lipiedmetabolisme van Mucor genevensis en verwante spesies ondersoek. Gevolglik is die endogene lipiedomset gedurende groei en ontwikkeling van die verskillende ongeslagtelike en geslagtelike voortplantingsfases van Mucor genevensis MUFS 038 bestudeer. Lipiedanalises is met tussenpose op kulture wat op soliede sintetiese media gekweek is, uitgevoer. Dit is gevind dat, gedurende al die ontwikkelingsfases, die lipiedsamestelling vergelykbaar was met die van 'n tipiese mucoraliese fungus. Zigospore het egter minder membrane (d.i. minder fosfolipiede) met 'n laer graad van vloeibaarheid (d.i. minder poli-onversadigde vetsure - POVs) gehad as sporangiospore en miselium. Afnames in neutrale, gliko- en fosfolipiede is waargeneem tydens sporogenese. Die doel van die volgende hoofstuk was om die opname en inkorporasie van araqidonsuur [20:4((06)] in die verskillende lipiedfraksies van Mucor genevensis MUFS 038 en Rhizopus oryzae PPRI 5172, te bestudeer. Die eksogene 20:4((,)6) is vinnig deur die fungi opgeneem. Die algehele konsentrasie 20:4((1)6) in beide fungi het afgeneem a.g.v. die katabolisme van 20:4((1)6). Die POV is geรฏnkorporeer in die neutrale, gliko- en fosfolipiede van beide fungi. Dit is gevind dat Rhizopus oryzae 'n groter vermoรซ as M. genevensis het om die hoeveelheid vrye 20:4((1)6) in die selle te verminder. Tydens inkubasie met 20:4((1)6), is verskillende veranderinge in die konsentrasies van 16- en 18-koolstof vetsure vir die twee fungi waargeneem. Dit dui op verskille tussen die lipiedmetabolismes van die twee fungi. In die volgende hoofstuk is mucoraliese fungi ondersoek vir die vorming van oksidasieprodukte vanaf eksogene POVs. Lipiedekstrakte van biomassa en vloeistoffases van kulture van die volgende stamme is geanaliseer d.m.V. gaschromatografie-massa spektrometrie: Mucor circinelloides f. circinelloides CBS 107.16, Mucor flavus CBS 234.35, Mucor genevensis MUFS 038, Mucor mucedo CBS 109.16, Mucor plumbeus CBS 111.07, Rhizopus oryzae PPRI 5172 en Thamnostylum piriforme MUFS 025. Die volgende POVs is vir die fungikulture gevoer: linoleiensuur, y-linoleensuur, dihomo-y-linoleensuur [20:3((1)6)], 20:4(0)6) en eikosapentanoรซsuur. Dit is gedemonstreer dat M. genevensis en M. circinelloides 3- hidroksie-5,8-tetradekadienoรซsuur (3-HTDE) vanaf 20:4((06) en 20:3((06) onderskeidelik, kan produseer. Geen ander 3-hidroksievetsure (3-0H-VSs) is in die ander stamme waargeneem nie. Dit word voorgestel dat die 3-0H-VSs in die meeste stamme teen te lae konsentrasies geproduseer is en dus nie waargeneem kon word nie. 'n Ander rede vir die skynbare afwesigheid van 3-0H-VSs kan wees dat hierdie verbindings vinnig deur hierdie stamme verbruik of verder gemetaboliseer word. Deteksie van 3-0H-VSs slegs in die vloeistoffase, het daarop gedui dat dit nie strukturele komponente van membrane was nie, of dat 3-HTDE gevorm is tydens 'n fisiologiese fase wat nie tot die finale biomassa bygedra het nie. Hierna is immunofluoressensiemikroskopie gebruik om die ligging van endogene 3-0H-VSs in M. genevensis MUFS 038 te bepaal. Dit is gevind dat 3-0H-VSs geassosieer word met spoordraende strukture. Dit is gespekuleer dat sommige lipiede, wat verminder tydens sporogenese van M. genevensis, getransformeer is na gehidroksileerde vetsure tydens sporogenese.
Description
Keywords
Lipid metabolism, Mucorales, Mucor genevensis, Rhizopus oryzae, Arachidonic acid, 3-hydroxy fatty acids, 3-hydroxy-5,8-tetradecadienoic acid, Immunofluorescence microscopy, Linolenic acids, Lipids -- Metabolism, Thesis (Ph.D. (Microbiology and Biochemistry))--University of the Free State, 1999